Hi David,
I could not reproduce your problem, so perhaps this has to do with the
document class you are using?
Here's a minimal example that produces the footnote mark when processed
with pdflatex:
\documentclass{article}
\begin{document}
This command can be used to produce several consecutive footnote markers
referring to the same foot note with:
\footnotemark[\value{footnote}]
\end{document}
Susan